1. Field of the Invention
The invention relates to a paper machine for producing a paper web with a former for sheet creation, a subsequent press section for dewatering, and a subsequent drying section for drying the paper web.
2. Discussion of Background Information
In the former of a paper machine it is generally customary to separate and remove an edge strip on each side. This serves to create clean, straight web edges which is an essential element for winding the paper web at the end of the paper machine. In the sections of the paper machine in between, much is done to maintain the quality of the web edges. In order to counteract the formation of folds as well as tears and rips, a guidance of the paper web as closed as possible, i.e., continuously, by a belt or a roll is desired. In particular with thin papers, certain press sections, and/or higher speeds, difficulties increasingly arise with regard to a stable web guidance. Here, the quality of the paper web is considerably influenced by edge separation or web flapping.
Therefore, the present invention ensures a good quality of the web edges at the end of the paper machine with the least possible expense.
The instant invention provides that, at least in the area of the press section and/or the drying section, preferably on both sides, at least one edge strip is separated and removed from the paper web. This allows the edge strips to be arranged according to endangered areas (with regard to a stable web guidance). This results in the possibility of limiting or even reducing the measures for ensuring a stable web guidance and also of ensuring clean and straight web edges at the end of the paper machine even in difficult circumstances (low basis weight, high speed, etc.)
Since energy is increasingly introduced into the production process of the paper web it is desirable to perform the separation of the edge strips as soon as possible and to introduce the edge strips into a pulper for recycling. For this reason, the edge strips should be separated and removed at the end of the press section, at the beginning of the drying section, or therebetween.
However, it can be advantageous for the glazing process to separate and remove the edge strips at the end of the drying section or behind it, i.e., in front of the glazing unit of the paper machine.
In addition, one edge strip each can still be separated and removed from the paper web in the former as well. In general, this first edge trimming should be larger than the subsequent one. However, for the purpose of limiting the expense, it is also possible to omit the edge trimming in the former.
The separation of edge strips from the paper web should occur by way of water jet devices with the paper web being supported by a belt, in particular in the form of a wire or a felt, or a roll. However, due to the high pressure of water jet devices it is generally advantageous for the paper web to travel without support during the separation of the edge strips since otherwise damages are to be expected to the belt or the roll. The removal of the edge strip should be supported by at least one scraper or similarly operating element which preferably guides the edge strips into the machine base.
The present invention is directed to a machine for producing a web. The machine includes a former for sheet formation of the web, a press section for dewatering the web, a drying section for drying the web, and at least one edge strip forming device positioned in an area of at least one of the press section and the drying section, which is arranged to separate at least one edge strip from the web.
In accordance with a feature of the instant invention, the machine can include at least one edge strip removing device positioned in an area of at least one of the press section and the drying section, which is arranged to remove the at least one edge strip separated from the web. The web may include a paper web and the machine is a paper machine.
Further, the at least one edge strip forming device may be arranged to separate the at least one edge strip from the web at an end of the press section, and the at least one edge strip removing device may be arranged to remove the at least one edge strip from the web at the end of the press section.
Still further, the at least one edge strip forming device can be arranged to separate the at least one edge strip from the web at a beginning of the dewatering section, and the at least one edge strip removing device can be arranged to remove the at least one edge strip from the web at the beginning of the dewatering section.
Moreover, the at least one edge strip forming device can be arranged to separate the at least one edge strip from the web at one of an end of the drying section or downstream of the drying section, and the at least one edge strip removing device can be arranged to remove the at least one edge strip from the web at the one of the end of the drying section or downstream of the drying section.
The at least one edge strip removing device may include at least one scraper. The at least one scraper may be arranged to guide the at least one edge strip into a machine base.
In accordance with another feature of the invention, an edge strip forming device may be positioned in the former, which is arranged to separate an edge strip from each side of the web, and an edge strip removing device may be positioned in the former, which is arranged to remove the edge strip separated from each side of the web.
According to still another feature of the present invention, wherein the at least one edge strip forming device may include a waterjet device. The at least one edge strip device can be arranged such that, during separation, a separation point of the at least one edge strip from the web is supported by one of a belt and a roll. Further, the belt can include at least one of a wire and a felt. The at least one edge strip device may be arranged such that, during separation, a separation point of the at least one edge strip from the web is not supported.
The present invention is directed to an apparatus for producing a web. The apparatus includes a former for sheet formation of the web, a press section for dewatering the web, a drying section for drying the web, at least one edge strip forming device positioned in an area of at least one of the press section and the drying section, which is arranged to separate at least one edge strip from the web, and at least one edge strip removing device comprising a doctor positioned in an area of at least one of the press section and the drying section, which is arranged to remove the at least one edge strip separated from the web.
The present invention is directed to a process of producing a web in an apparatus that includes a former, a press section, a drying section, and at least one edge strip forming device positioned in an area of at least one of the press section and the drying section. The process includes forming the web on the former, dewatering the web in the press section, drying the web in the drying section, and separating, with the at least one edge strip forming device, at least one edge strip from the web in the at least one of the press section and the drying section.
In accordance with a feature of the invention, the apparatus may further include at least one edge strip removing device positioned in an area of at least one of the press section and the drying section, and the process can further include removing, with the at least one edge strip removing device, the at least one edge strip separated from the web in the at least one of the press section and the drying section.
Further, the at least one edge strip forming device and the at least one edge strip removing device may be positioned at an end of the press section, and process can further include separating, with the at least one edge strip forming device, the at least one edge strip from the web at the end of the press section, and removing, with the at least one edge strip removing device, the at least one edge strip separated from the web at the end of the press section.
Still further, the at least one edge strip forming device and the at least one edge strip removing device can be positioned at a beginning of the dewatering section, and process may further include separating, with the at least one edge strip forming device, the at least one edge strip from the web at the beginning of the dewatering section, and removing, with the at least one edge strip removing device, the at least one edge strip separated from the web at the beginning of the dewatering section.
Moreover, the at least one edge strip forming device and the at least one edge strip removing device can be positioned at one of an end of the dryer section or downstream of the dryer section, and process can further include separating, with the at least one edge strip forming device, the at least one edge strip from the web at the one of the end of the dryer section or downstream of the dryer section, and removing, with the at least one edge strip removing device, the at least one edge strip separated from the web at the one of the end of the dryer section or downstream of the dryer section.
The at least one edge strip removing device can include at least one scraper and the process can further include guiding the at least one edge strip into a machine base with the at least one scraper.
In accordance with another feature of the present invention, the apparatus may further include an edge strip forming device and an edge strip removing device positioned in the former, and the process can further include separating an edge strip from each side of the web with the edge strip forming device in the former, and removing the edge strip separated from each side of the web in the former.
According to still another feature of the invention, during separation, a separation point of the at least one edge strip from the web may be supported by one of a belt and a roll.
In accordance with yet another feature of the instant invention, the web may be supported by one of a belt and a roll from the former section through the dryer section.
The present invention is directed to a process of producing a web in an apparatus that includes a former, a press section, and a drying section. The process includes forming the web on the former, dewatering the web in the press section, drying the web in the drying section, and separating at least one edge strip from the web in at least one of the press section and the drying section.
Further, the process may include removing the at least one edge strip separated from the web in the at least one of the press section and the drying section.
Other exemplary embodiments and advantages of the present invention may be ascertained by reviewing the present disclosure and the accompanying drawing.